Adobe Digital Editions cannot open my purchased Google Books

I purchased a book from Google Books, and I wanted to read the book when there's no internet connection, so I tried to download the book; that did not work.....then I downloaded Adobe Digital Edition, and when I try to download book off Google (either EPUBS or via PDF), Adobe Digital Editions is unable to import it. I receive a message that says: Unable to download   Error getting License. License Server Communication Problem: E_ADEPT_NO_TOKEN.  What could be preventing Adobe Digital Edition from being able to open the file? I authorized my device to do so, after all.